About Lighting: Lights and Shadows

[H. Ikeda]

After '[digital] Lighting & Rendering', spotlights with soft shadows (shadow map), and omni and other lights with hard shadows (raytracing shadows).
Also, shadow-only lights seem useful.
Is there any way to make a shadow-only light or its fake in c4d?

[hmmdonuts]

Shadow only lights can be accomplished by setting up a regular, shadow casting light, copy it and set the copies brightness to the negative of the original. Turn off shadows on the copy, too.

cheers

hmmdonuts

[H. Ikeda]

Negative brightness is possible in c4d? :shrug:

[flingster]

negative brightness is possible..isn't it!

shadow maps thread i was having problems with render times awhile ago.
http://www.cgtalk.com/showthread.php?s=&threadid=75682

lighting thread
http://www.cgtalk.com/showthread.php?s=&threadid=63423

default setups thread...mentioned lighting setups
http://www.cgtalk.com/showthread.php?s=&threadid=65313

"Also distant lights with area shadows are meaningless and these seem equal to hard shadows"
what about playing with width and falloff...won't this change hardness?...mmmm maybe not.
sorry can't help you a bit more bud....jaggies bit is probably cureable.

[AdamT]

Originally posted by H. Ikeda
Negative brightness is possible in c4d? :shrug:
Of course! But you have to use the brightness setting in the Details tab rather than the General tab.

[H. Ikeda]

AdamT: thanks, it's light, no, right!:) :drool:
flingster: thanks for the links. I know them but didn't check them out thoroughly. Jaggy things may be cured or bugs, I'll think about it.

[H. Ikeda]

The jaggy problem seems to be in connection with basic algorithms in c4d.
Without shadow option, an object is only shaded in shading model such as Phong, and with shadow options, 'shade' by the shadow is add to the shaded part, because it might also be a unlit part together with usual 'shadow' on the ground.
And in some cases, this 'shade by shadow' on a polygon surface shows jaggy pattern like:

http://www.interq.or.jp/aquarius/ikeda3dr/data/cgtalk/shadows.jpg

This is a polygon sphere from Hexahedron, and no apparent jags in pure sphere (primitive).
And with brighter shading such as Blinn or Oren-Nayar, this may become clear, because of the mismatch between shading and 'shade by shadow'.
Use of HyperNURBS may be a way to cure this, but not perfect.

[JamesMK]

Those jaggies in shadowed areas are usually cleaned away by adjusting the shadow bias.

[H. Ikeda]

JamesMK: thanks for the reply. In cases of soft shadows, it could be. But what about hard and area shadows as above?:rolleyes:

[JamesMK]

Hmm, that might be different of course, no bias to play with there, right?

I can't make any experiments right now, since my 3D workstation just decided to slap a hardware failure in my face this morning... Ack... I hope someone has some suggestions before I can get back to C4D in a week or so :annoyed:

[brammelo]

Originally posted by JamesMK
I can't make any experiments right now, since my 3D workstation just decided to slap a hardware failure in my face this morning... Ack... I hope someone has some suggestions before I can get back to C4D in a week or so :annoyed:

Yes: get a new workstation ;)

(ok, this was a silly one, but one can't always be intelligent)

Cheers,
BaRa

[H. Ikeda]

brammelo: everyone has own intelligence and own stupidity. That's human. Don't worry about yourself, worry about something you love.

[JamesMK]

Originally posted by brammelo
Yes: get a new workstation ;)
He he, pretty funny! Unfortunately that's not possible. I'll just have to get a new power supply, since that's what is broken.

HOWEVER, I meant "suggestions" about solving the jagged shadowing issue...

[JIII]

umm its just the stock answer but have you played with your ray depth and shadow map size at all?

ohh yeah but a new computer james.

just kiddin man.

[H. Ikeda]

Thanks JIII, but there is no change for ray depths from 0 to 50, as is expected in such simple scenes. It's same with shadow depths.

[flingster]

what do maxon say about it....try there support people?
:thumbsup:

[H. Ikeda]

flingster: you may be right, but I'd like to wait for repair of JamesMK's workstation before that.

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